In the existing technology, the rail of the garage door opener arranges a trolley member which is connected to the garage door by a connecting rod. In normal condition, the trolley is connected to the chain, and the motor drives the chain moving, thus, the chain drives the trolley member moving in the rail which causes the garage door opening or closing. In the urgency condition (such as the motor is broken), the garage door is moved by manual, and at the same time, the trolley member is needed to detach from the chain, thus, the manual causes the garage door moving. The existing trolley member has two steady working status, so once the motor is changed from power off to power on, the trolley member may still be detached from the chain, thereby the motor can drive the idling chain, and the chain can not be driven to move the trolley and then the garage door.